Refrigerant evaporator



Sept. 9, 1941. D. F. NEWMAN REFRIGERANT EVAPORATOR Filed Nov. 1, 1959 nventov-c De\be1-t F Newman,

6,! is Attorn ey.

hanted Sept. 9, 1941 REFRIGERANT EVAPORATOR Delbert F. Newman,Schenectady, N. Y., assignor to General Electric Company, a corporationof New York Application November 1, 1939, Serial No. 302,376

2 Claims. (01. 62-126) My invention relates to refrigerant evaporators,and particularly to evaporators of the flooded type constructed fromsheet metal.

Evaporators for household refrigerating machines are commonlyconstructed of sheet metal,

a double wall structure being provided by bending a single sheet onitself or by securing separate sheets together and providing suitableindentations between the wall portions to form the required refrigerantpassages. When metals of high thermal conductivity, such as copper,copper alloys, or aluminum, are employed, the thickness of the sheetsmakes little difference in the efficiency of the evaporator. However,when it is desired to construct an evaporator of other metals, uch asstainless steel, which have relatively low coeflicients of thermalconductivity, it becomes desirable to employ much thinner sheets inorder to reduce the thickness of metal through which the heat is to betransferred from the medium to be cooled to the refrigerant. Thethickness of material which may be employed is, of course, limited bythe pressure to be maintained in the evaporator as it is desirable toavoid any deformation of the evaporator surface due to pressure. Suchdeformation is a particular disadvantage in evapoi'ators having shelvesfor supporting freezing trays and the like since it is essential that asgreat -a portion of the refrigeranj t conduit surface as Possible bemaitained flat and be available to contact the surface of the freezingtray. If the surface of the shelf adjacent the refrigerant conduitsshould become bulged due to pressure in the evaporator, the effectiveheat conducting area in the shelf will be greatly'reduced. Accordingly,it is an object of my invention to provide a refrigerant evaporatorwhich may be constructed of thin sheet metal and which will effectivelyresist deformation' due to pressure within the refrigerant passagesthereof. Another object of my invention is to provide an evaporator ofthe flooded type constructed of sheet metal and having a header formedin a plurality of sections so arranged as to effectively preventdeformation of the evaporator surface due to pressure of the refrigeranttherein. 1

Further objects and advantages of my inven- I tion will become apparentas the following description proceeds, and the features of novelty whichcharacterize my invention will be pointed out with particularity in theclaims'annexed to and forming-a partfl'of this specification.

For a better understandingof my invention, reference may be had to theaccompanying drawing in which Fig. 1 is a perspective view of anevaporator embodying my invention; Fig. 2 is a front elevation view ofthe evaporator shown in Fig. 1; Fig. 3 is an enlarged sectional view onthe line 3-3 of Fig. 2; Fig. 4 is an enlarged sectional view on the line4-4 of Fig. 2; and Fig. 5 is a plan view of the double wall structure ofthe evaporator shown in Fig. 1 before bending.

Referringnow to the drawing, in Figs. 1 and 2, I have shown 'a floodedevaporator of the type \employed in household refrigerating machinesfrom the header per freezing chamber I1.

and comprising a double walled structure of bshaped cross-sectionproviding vertical walls l0 and II and horizontal freezing traysupporting shelves l2 and I 3, the Wall [3 having a flange I4 welded orotherwise secured to the wall l0 and forming ;with the other walls alower freezing chamber. IS. A sheet metal wall [6 is secured to the topof the vertical wall II and, together with the upper portion of the wallIt], provides an up- The upper ends of the Walls l0 and I6 are providedwith horizontal flanges I8 and I9 respectively which are adapted to besecured to the top wall of the refrigerator cabinet liner, holes 20 and2| being provided in the flanges l8 and IQ for this purpose. The doublewall portion of the evaporator is constructed from inner and outercomplementary sheet metal portions 22 and 23 respectively, as indicatedin Figs. 3 and 4. In constructing the double wall portion, the sheets 22and 23 while flat are stamped with suitable indentations to form thenecessary refrigerant header and circulating refrigerant passages andare then secured together in face engagement while fiat, as shown inFig.

5, the sheet 23 being shown on the top. 'The 1 sheets 22 and 23 areprovided with parallel semicylindrical indentations near one end thereofwhich cooperate to provide two cylinders 24 and 25 connected by passages26 at their ends and constituting a header for the separation of liquidand gaseous refrigerant. A portion of the sheets 22 and 23 forming astrip of wall 21 between the cylinders 24 and 25 are securely welded orotherwise suitably bonded together. The sheets. 22 and 23 are providedwith U-shaped indentations 28 and 29 respectively, which formrefrigerant, circulating passages communicating with and depending fromthe lower cylinder 25 of the header. The passages 28and 29 extendthrough the wall In and across the freezing shelf l2. A sinuous conduitis formed in the walls II and I3 by indentations 30 and 3l 1n the walls22 and 23 respectively, and terminates in a manifold 32 formed byindentations in the outer sheet 23. A plurality of refrigerant injectingducts 33 are provided to convey refrigerant from the manifold 32 to thelower portions 'of the U-shaped refrigerant passages formed by theindentations 28 and 29. The fiat double wall structure shown in Fig. 5is bent along the dotted lines after the sheets have been welded alongtheir edges and between the indentations to provide the b-shapedstructure shown in Figs. 1 and 2, and the flange I4 is welded orotherwise suitably secured to the wall ID. The sheet metal wall I6 isthen welded or otherwise suitably. secured to the wall II to enclose theupper freezing chamber. v

A'liquid line 34 is provided to admit refriger- Y ant to the evaporatorand communicates through trapezoidal cross-section particularly in theshelf areas, it is possible to construct an evaporator of thin sheetmetal of relatively low conductivity a passage 35 with the sinuousconduit formed in the walls l2 and I3. Refrigerant vaporized in theevaporator is removed through a suction line 36 arranged to conduct thevapor from the upper cylinder 24 of the header.

The cylinders 24 and 25 and the connections 26 form a header ofsufficient volume to provide for a proper separation of liquid andgaseous refrigerant andto maintain the U-shaped passages flooded withliquid refrigerant at all times. By

I providing the two relatively small parallel cylinders instead of asingle header, less pressure is exerted along the walls where the sheets22 and 23 are'jointed around the header and between the cylinders and athinner gauge sheet metal may be employed to construct a header of thistype than would bepossible with a single header. The U-shapedindentations 29 in the outer sheet 23 are of rounded cross-section andeffectively resist deformation due to pressure. It is essential, I

which the pressure acts. In this manner, arefrigerant conduit or passageis provided which 4 is of sufiicient size to carry the required quantityof refrigerant and provides the flat surface nec-- essary for contactwith freezing. trays and the like. It has been found desirable to formthe :sinuous conduitin the walls II and I3 so that it has a smallercross-sectional area than the U- shaped passages in the other walls, andI. therefore, have illustrated the indentations 30 and 3| as havingtrapezoidal cross-sections. The conduits 3| and the shelf I3, therefore,present a 'flat surface of substantial area in contact with the freezingtrays and deformation of the walls of the indentations in both the innerand outer sheet metal portions is prevented.

By constructing the header of two cylindrical portions and by providingthe indentations of which will effectively resist deformation due topressure and also effectively increase the capacity of the evaporatorbecause of the reduced thermal resistance of the walls thereof.

While I have described my invention in connection with an evaporator forhousehold refrigerators, I do not desire my invention to be limited tothe particular construction shown and de-,

scribed, and I intend in the appended claims to cover all modificationswithin the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. An evaporator of the flooded type for refrigerating machinescomprising complementary sheet metal portions secured together in faceengagement and formed to provide at least one vertical wall, said sheetmetal portions having indentations therein near the top of said verticalwall forming two parallel horizontally extending substantially identicalcylinders of relatively small diameter and passages connecting saidcylinders at their ends to constitute said cylinders a liquid and vaporseparating header, said'sheet metal portions being securely bondedtogether between said indentations, at least one of said sheet metalportions having a plurality of parallel indentations formed therein toprovide refrigerant passages communicating with and depending from thelower one "of said cylinders, means for admitting liquid refrigerant tosaid passages, and means for conducting vaporized refrigerant from theupper one of said cylinders.

2. An evaporator of the flooded type, for re-v frigerating machinescomprising complementary sheet metal portions secured together in faceengagement and formed to provide at least one vertical wall and afreezing shelf, said sheet metal portions having indentations thereinnear the top of said vertical wall forming two parallel horizontallyextending substantially identical cylinders and passages connecting saidcylinders at'their ends to constitute said cylinders a liquid andvaporseparating'header, said sheet metal portions being securely bondedtogether between said indentations, said sheet metal portions having aplurality of complementary indentations formed therein to providerefrigerant circulating passages communicating with said header, theindentations in the sheet metal portion forming the bottom surface ofsaid shelf being of rounded cross-section and the complementaryindentations -formed in the upper surface of said shelf being ofsubstantially trapezoidal cross-section whereby a fiat surface isprovided along said refri'gerant passages in said shelf and saidindentations are adapted to resist relatively high pres-,

DELBEBT F. NEWMAN.

